This invention relates generally to electrical switch assemblies and more particularly to a sealed elastomeric backlit switch wherein the housing and pushbutton are formed as a unitary elastomeric molding which can be sealingly clamped to a mounting panel.
Push button operated electrical switches, including backlit switches, are widely used in numerous applications. Many of these applications are in environments which are rather benign to electrical switches so that the switches are not exposed to either very high or low temperatures, moisture, potential hard use or even abuse.
In prior art fuel dispensing installations, such as in gasoline service stations, the electrically powered fuel dispenser pump is conventionally actuated by moving a lever which operates an electrical switch located inside a protective housing. Some prior art fuel dispensing installations provide a separate exposed switch assembly which the operator must operate to activate the dispenser. Such switch assemblies, due to the location of the dispenser in an outside environment, must be designed to operate in temperatures in the range of -40.degree. C. to +85.degree. C. and must also be sealed to withstand rain, snow and ice as well as hard use. Some prior art fuel dispensing installations have provided push button switches for activating the dispenser which use a rubber or vinyl boot to seal the switch assembly. Such switches have the disadvantage that the rubber or vinyl boot material is easily ripped or torn thereby exposing the internal switch mechanism to the elements. Still other prior art fuel dispensing installations have been provided wherein a relatively large push button switch assembly is provided for direct actuation of the electrical switch by an operator. These assemblies are quite expensive and also require a substantial amount of space.
A new type of self service fuel dispensing installation has recently come into use whereby the operator may select either a credit card transaction or a cash transaction. For that reason, it has become desirable to provide a lighted push button dispenser actuation switch so that the customer is reminded to depress a switch for either a cash or credit transaction. In certain of these dispensing installations, several push button switches are provided whereby the switch lights will flash to direct the operator's attention to the need to depress one of the switches. It is important, therefore, that the switch assembly be "user friendly" and is easy to operate. For aesthetic reasons, it is also desirable that such actuation switches may be designed to have a low profile so that they do not extend a very great distance from the front panel of the dispenser.
The cost of providing such switches for such types of fuel dispensing installations may be substantial. For instance, in a large dispenser having four pumps each on two sides of a dispensing island, twenty-six (26) such switches would need to be provided for certain types of dispensing installations.
An additional requirement for a push button actuated switch assembly used in a fuel dispensing installation is to provide positive feedback to the operator, that is to say, to provide sufficient positive movement during actuation of the switch so that the operator is aware that the switch has been actuated. In certain prior art switches, the movement for actuation of a switch is so limited that the operator is not aware, due to a lack of positive feedback, that the switch has actually been actuated.
Prior art switches have been provided with elastomeric elements for both sealing purposes and to give the switch a desired "feel". However, none of these prior art push button switches has been satisfactory to withstand the rugged fuel dispensing installation environment. Such prior art sealed switches have also utilized numerous parts, thereby not only adding undesired expense but also causing the switches to be subject to undesired malfunctions and breakdowns.
It is therefore desired to provide an elastomeric backlit switch suitable for use in rugged environments, which is simple in construction, relatively inexpensive to manufacture, and is not subject to failure.
While the invention described hereinafter is suitable for application in fuel dispensing installations, it should be understood that the invention is not limited to such use and may be used in numerous other applications, particularly those applications wherein a relatively simple and inexpensive switch assembly is needed which has a long life, which can withstand a great range of temperatures and which can be sealed from moisture or other harmful substances.